BERLIN — Please do not call Mark Gould a Nazi hunter.

He finds the phrase demeaning.

Mr. Gould prefers this description: A 43-year-old college drop-out from Los Angeles who says he made a lot of money in finance, became interested in Nazi memorabilia and ended up on an undercover odyssey where he befriended a former Waffen SS officer and recorded many of their conversations with the plan to someday expose the man’s role in the Third Reich.

But an alternative description might read like this: A man on a self-appointed mission to expose an aging Nazi — one who has published an autobiography and has never been accused of war crimes — and hoping, in the process, to publish a book and land a movie deal.

Whatever the subtext, on Saturday Mr. Gould revealed his ruse to 97-year-old Bernhard Frank, once a trusted aide to Heinrich Himmler, the second most powerful man in Nazi Germany. Mr. Frank looked at his accuser and through the confusion of age and betrayal asked: “Are you my enemy or my friend?” according to a transcript of the encounter provided by Mr. Gould.

“I am your enemy,” Mr. Gould said, leaning in toward Mr. Frank. “I am your enemy.”

Mr. Gould announced on Tuesday that he and his cousin, Burton Bernstein, are filing a federal civil lawsuit against Mr. Frank in Washington that will assert that the ex-Nazi officer is responsible for orders issued on July 28, 1941, that spurred SS troops to kill their ancestors in an attack on the village of Korets, in Ukraine. Mr. Gould says he can provide documentary proof that Mr. Frank had a central role in the administration of the earliest days of the Holocaust as a desk officer who facilitated the machinery of Nazi death. This charge, however, has been dismissed by other experts on the Holocaust as overstated.

The suit will close out the unlikely journey of a self-styled historian with unorthodox techniques, and bring to an end his staged friendship with a former Nazi officer who confided in one taped interview that Himmler “was a good man” and that the Jews “dug their own grave” by oppressing the Germans.

“My enemy, Why?” Mr. Frank demanded according to the transcript.

“Because you killed my family,” Mr. Gould replied.

Mr. Frank has not been in hiding, and he is not regarded as a war criminal by the authorities in Germany who are responsible for policing the Nazi past.

Indeed, four years ago Mr. Frank published a book here about his Nazi career, called “As Hitler’s Commandant — From the Wewelsburg to the Berghof,” complete with photographs of himself as a dashing young officer in uniform. He has also appeared on German television in shows about the Third Reich.

During the Nazi era, he served as a librarian at Wewelsburg Castle, the ideological training ground for the SS. He subsequently occupied a senior position in Himmler’s administrative staff, keeping what was called the war diary. He co-signed some of Himmler’s orders for what was called “correctness” and later served as a commander in the Eastern Front. He eventually was made commander of the Obersalzberg, the site of Hitler’s mountain retreat, the Berghof. Toward the end of the war, Mr. Frank was ordered to arrest and kill Hermann Göring, an order which he defied.

All that is in Mr. Frank’s book.

Kurt Schrimm, chief of the Federal Archives Central Office for the Investigation of Nazi Crimes in Germany said that Mr. Frank’s name appears in the archives but never in connection with war crimes. Other Nazi experts also said that Mr. Frank was not linked to war crimes.

In a telephone interview from his home in Frankfurt, Mr. Frank said he knew nothing about the Holocaust, a statement that seems doubtful given his administrative role in Himmler’s office. “I’ve never done statements concerning the Holocaust, because I just don’t exactly know much about it,” Mr. Frank said. “You have to be careful with statements. Do you understand?”

Asked about Mr. Gould, he said at first that he was not sure who he was and then added: “I have the feeling that he sells my words different, with a different value, so unreliable.” His voice was weak and cautious.

“Was Mr. Gould friendly?” he was asked.

“Well, what seller, who wants to sell something, is not friendly,” he replied.

Mr. Gould is the most unlikely of accusers.

To begin with, he is not Jewish.

He says he has an “extended Jewish family,” because his mother married a Jewish man who adopted him. He tells of a rough and tumble upbringing, recalling a childhood in Texas marked by fighting, heavy drinking and drug use. He said he was in rehabilitation by the time he was 18, dropped out of college and started selling stock. He said he realized he could make money selling lists of investors, created his own company, moved to Los Angeles with his girlfriend with whom he had three daughters. He was speaking to a coin dealer one day for business when he saw the man was also selling a Nazi flag.

He bought the flag and started buying up World War II memorabilia, which he stored in his Los Angeles apartment. One day he said he purchased the gun Hermann Göring surrendered to the Americans. He said he learned the weapon had been turned over to an American soldier, who was a Jew.

He said he saw that as a bit of poetic justice.

He said that inspired him to film members of the team who arrested Mr. Göring. He then decided to take his video camera to Germany. He realized quickly, he said, that he could penetrate deep into the neo-Nazi community if he presented himself as a wealthy sympathizer.

The more he purchased Nazi memorabilia, the deeper he penetrated.

“I have been living underground for a long time now,” Mr. Gould said one day seated in an office in Berlin. He has grown his hair long now, a backlash to the years he had to remain clean cut as a neo-Nazi. “I lived in that world. I saw things in a National Socialist point of view. I compartmentalized my life.”

His road to Mr. Frank’s home is impossible to verify. He suggests that intelligence agencies here helped him cover his tracks in exchange for inside information on the neo-Nazi movement, but that claim could not be verified. It also remains unclear where the money came from for all of his work, and some experts he met over the years said they chose not to be involved with him because they were dubious about his tactics — including hidden cameras — and skeptical of his goals.

Mr. Gould says he was secretive over the years because he did not want to reveal Mr. Frank’s identity. There are also some academics in the United States and officials in Israel who have verified meeting Mr. Gould in Los Angeles and in Tel Aviv and being impressed with his work.

“I think Mark is an unconventional guy who has done courageous and lonely work,” said Stephen D. Smith, executive director of the Shoah Foundation Institute at the University of Southern California and founder of the The Holocaust Center in Britain.

After reviewing the material, he said he thinks Mr. Gould’s work raises an important question of how society defines culpability. “Of all the Nazi’s that have surfaced over the years, Bernhard Frank sends the biggest shiver down my spine,” Mr. Smith wrote in an essay. “Not because he was an outright killer, but because he was active right in the heart of darkness, at the epicenter of the Holocaust, at the scene of the crime. For some reason we let him get away with it.”

Holli Levitsky, director of the Jewish Studies Program at Loyola Marymount University, said she reviewed all of Mr. Gould’s findings and believes he has connected dots that had previously been ignored or missed.

“I strongly believe he is what he says he is: a Nazi-hunter with a live specimen whom Mark has every right to get credit for uncovering,” she wrote in an email, noting that Mr. Gould likely rankles traditional historians because of his untraditional approach.

Mr. Gould swept into Germany last week to complete his project. He was traveling with his companion, Danica Bernard, and a nephew. The three entered Mr. Frank’s home on Saturday. Mr. Frank was with his nurse and a friend. According to the transcript Mr. Frank kept shouting, “nothing, nothing, nothing,” waving a hand and at one point feigning going to sleep

Mr. Gould was excited and the cameras were rolling:: “You’ll be dead soon,” he said before he left. “And the whole world will know.”

nytimes.com